Device for fixing an air-gap winding of a dynamo-electric machine

ABSTRACT

An electric machine includes a stator lamination packet having an inner periphery defining a stator bore, a laminted screening packet with an inner periphery and lamination segments formed of magnetic material, and a slot and tooth system disposed on and connected to the inner periphery of the screening packet, the slot and tooth system being at least partly formed of nonmagnetic material and having successive slot teeth defining bar receiving slots with a slot bottom, and an air-gap winding on the inner periphery of the stator lamination packet having winding bars with winding bar sides oriented toward the stator bore, the winding bars being inserted in the bar receiving slots with a radial protrusion beyond the slot teeth. A system for fixing the air-gap winding on the inner periphery of the stator lamination packet and a method for assembling and dismantling the system include a retaining device pressing the winding bar sides against the slot bottom, the retaining device having a multiplicty of elastic support rings being mutually aligned in axial direction of the electric machine and having outer peripheries, the support rings having at least one dividing seam formed therein, a turnbuckle inside the stator bore in the vicinity of the at least one dividing seam for varying the diameter and adjusting azimuthal prestressing of the support rings, and spring elements inserted between the outer peripheries of the support rings and the winding bar sides.

The invention relates to a system for fixing an air-gap winding on theinside circumference of the stator lamination packet of high-powerdynamo-electric machines, in particular turbo-generators

A) wherein the stator lamination packet that with its insidecircumference defines the stator bore for the machine rotor revolvingwith an air gap is composed of the following:

A1) a laminated screening packet of approximately circular-annular crosssection in the yoke region, the lamination segments of which comprisemagnetic material,

A2) and a slot and tooth system disposed on the inside circumference ofthe screening packet, which system, at least in the vicinity of thebore, comprises nonmagnetic material and at abutment points, which aredistributed over the inside circumference of the screening packet, isrigidly connected to the screening packet,

B) wherein the winding bars of the air-gap winding can be inserted, witha radial excess protrusion protruding beyond the slot teeth into the airgap, into the circumferential interstices serving as axially parallelbar receiving slots, which are each defined in the tangential directionby successive slot teeth, and are fixable in their introduced positionby means of a retaining device resting with a large area of contactagainst the winding bar sides oriented toward the stator bore andpressing the winding bars against the slot bottom.

A system of this kind is known from German Patent 29 24 863. There, theindividual slot segment bar groups are covered by pressure stripsextending axially of the machine, and in the space between two pressurestrips tangentially adjacent one another, radial clamping screwsdistributed over the length of the lamination packet are disposed in thevicinity of the slot teeth, these screws being screwed into anchoragepoints of the lamination packet. These screws for instance compriseaxial bolts provided with radial threaded bores and insulated on theoutside, which are inserted into corresponding axial bores of thelamination packet. On their outer end, the clamping screws engage theside region of the two tangentially adjacent pressure strips, by meansof retaining strips extending axially of the machine. In this knownsystem, the tooth region is thus occupied by the clamping screws for theradial tensioning. The tangential tensioning is not mentioned in thisGerman Patent; it might be possible, by the insertion of suitable wedgesinto the set of slot segment bar groups, to convert a portion of theradial tension forces into tangential bracing forces. However, in thatcase the means for radial and tangential bracing of the air-gap windingwould not be independent of one another within the various bar receivingslots.

The same is true for a further system of this generic type for fixing anair-gap winding as described in German Published, Prosecuted PatentApplication DE-AS 21 65 678. There, for radial bracing of the statorwinding bars placed in the slots of a slot-and-tooth system, aninsulating cylinder is introduced into the stator bore of the statorlamination packet, but on the condition that the stator winding bars, intheir inlaid state, still have a certain radial protrusion beyond theslot teeth, so that by means of the introduced insulating cylinder thebars can be pressed against the base of the slot, far enough that theoutside circumference of the insulating cylinder rests on the tops ofthe teeth. The assembly or dismantling of an insulating cylinderextending over the entire lamination packet length, and which forbringing to bear the required radial bracing forces must have a certainwall thickness, prove to be very difficult. Furthermore, as indicated,only a radial bracing is effected with the insulating cylinder, and iftangential bracing forces were also generated by means of suitablewedges, then it would not be possible to adjust the radial andtangential bracing independently of one another.

It is the object of the invention to embody the generic system forfixing an air-gap winding such that the region of the axial set of slotteeth can be kept free of clamping elements for the radial bracing ofthe winding during operation, or at least can be embodied such that itbecomes possible to accommodate separately adjustable clamping elementsfor tangential bracing in this region. It should be possible to bringconsiderable radial clamping forces to bear on the entire insidecircumferential surface of the slot segment bar groups, or of the barsof the air-gap winding, and these forces as well should be adjustable.The novel retaining device should occupy little space inside themechanical air-gap and should also be easy to assemble, test andoptionally re-clamp in the event that maintenance work is done.

According to the invention, this object is attained, in a system of thisgeneric type for fixing an air-gap winding, by means of the followingcharacteristics:

a) the retaining device has a multiplicity of support rings in line withone another axially of the machine, which comprise elasticallydeformable, resilient material, which are divided at least at one pointalong their circumference and are adjustable in their azimuthalprestressing by means of diameter enlargement in order to generate aradial prestressing force engaging the winding bars, which is greaterthan the operating force, and

b) the supporting rings, for diameter variation upon their assembly anddismantling as well as for post-tensioning, are provided inside thestator bore, in the vicinity of at least one of their dividing seams,with a turnbuckle. Various embodiments of the locking wedge for theturnbuckle.

In accordance with another feature of the invention, the dividing seamlateral surfaces or "flanks" as they will be referred to below, whichare facing one another at a distance of the support rings belonging tothe turnbuckle taper from radially inward to radially outward over atleast a partial distance and can be brought into engagement with thecorrespondingly shaped counterpart flanks of a tensionable lockingwedge, upon the displacement of which in the clamping direction thepressure exerted per unit of surface are between the dividing seamflanks and the counterpart flanks is increased.

In accordance with a further feature of the invention, the dividing seamflanks facing one another at a distance of the support ring endsbelonging to the turnbuckle taper or widen from radially inward toradially outward over at least a partial length and widen or taper overat least an adjoining partial length, so that the two support rings formarrowhead-like protrusions or arrow-tail-like recesses alignedazimuthally with one another, which face one another in pairs.

In accordance with an added feature of the invention, the turnbuckle isclampable by means of relative displacement of the locking wedgecounterpart flanks with respect to the dividing seam flanks in theradial direction.

In accordance with an additional feature of the invention, thecorresponding flank portions of the support ring ends and of the lockingwedge extending in tapering or enlarging fashion, respectively, in theradial direction extend tapering in wedge-like fashion in an axialinsertion and clamping direction of the locking wedge, having a wedgeangle such that self-locking occurs.

In accordance with yet another feature of the invention, the lockingwedge, as viewed in the radial direction in its installed state has anapproximately trapezoidal bottom face and has an adjusting screworiented in its axial insertion direction let into its rearward endportion, with the shaft end of which, protruding beyond the contour ofthe support ring, the locking wedge of the turnbuckle of an axiallyadjacent support ring can be brought into contact, in such a manner thatwith turnbuckles, disposed in axial alignment with one another, of theaxially aligned and assembled support rings, the preceding locking wedgeof a given aligned pair is fixed in its adjusted position by therespectively succeeding locking wedge, with the respective first andlast support ring in the axial set being axially fixed at the slot andtooth system.

In accordance with yet a further feature of the invention, the adjustingscrew is embodied as a stud bolt and is supported with its threadedshaft in a threaded blind bore of the rearward end portion of thelocking wedge and on a free end adjoining the threaded shaft has athreaded polygon for access by monkey wrenches, as well as having theprotruding shaft end adjacent thereto, and that in the vicinity of thefree end of the adjusting screw, the rearward end portion of theassociated locking wedge and/or the contacting face end of the adjacentsupport ring is set back or recessed for the sake of accessability tothe threaded polygon. Pressure-distribution and spring elements, whichare introduced as pressure-transmitting elements between the outercircumference of the support ring and the inner circumference of thesides of the bars are provided or follows.

In accordance with yet an added feature of the invention, springelements, in particular strip-like wave springs, are inserted in betweenthe outside circumference of the support rings and the abutting windingbar sides.

In accordance with yet an additional feature of the invention, springguide beds having the cross section of a flat U are introduced inbetween the wave springs and the support rings, the wave springs beingreceived by the U-shaped channel of the spring guide beds.

In accordance with still a further feature of the invention, the supportrings preferably comprise fiber-reinforced synthetic resin (FvK),because support rings of this material have a relatively low eight, thatis, a low weight in comparison with steel, and nevertheless can exertconsiderable spring-elastic bracing forces.

In accordance with still an added feature of the invention, the windingbars or the slot segment bar groups are supported with prestressing bypressure pieces disposed on the top of the slot teeth, and the pressurepieces are retained by means of clamping screws disposed radially in thevicinity of the slot teeth and anchored in abutments of the statorlamination packet, the pressure pieces and the clamping screws areradially outwardly recessed with their heads with respect to the outsidecircumference of the support rings, and the pressure pieces, fortangential prestressing of the winding bars, engage the heads of wedgestrips, which are inserted into wedge interstices between the slot teethand the respective contacting winding bar side. These features attainsecondary object of further embodying the system according to theinvention such that in addition to the radial bracing by means of thesupport rings and regardless thereof, a separately adjustable tangentialbracing for the bars or the slot segment bar groups can be disposed inthe vicinity of the axial set of slot teeth and performed, withouthaving to provide inflatable pressure hoses for this purpose insidespaces between the bars.

Based on the known system for fixing an air-gap winding in accordancewith German Patent 29 24 863 mentioned above, in which the winding bars,or the slot segment bar groups, are supported with initial tension bymeans of pressure pieces disposed on the head of the slot teeth and thepressure pieces are retained by means of clamping screws disposedradially in the vicinity of the slot teeth and anchored in abutments ofthe stator lamination packet, the secondary object is attained by thecharacteristics disclosed in the preceding paragraph, and a furtherembodiment of that system is disclosed by means of such feature, inaccordance with still an additional feature of the invention, in that inradial alignment with the heads of the clamping screws, openings in thesupport rings are provided, through which a clamping tool can engage theheads of the clamping screws, accessing them from the insidecircumference of the stator bore. Post-tensioning of the tangentialbracing is made possible even with the support rings int he assembledstate.

The subject of the invention is also a method for assembly anddismantling of a system as defined by the aforementioned features insidethe stator bore, by means of which the object is attained of adaptingthe disposition of the support rings over the entire axial length of thestator lamination packet to the fact that the winding bars or theindividual slot segment bar groups can be assembled only in successionon the inside circumference of the the stator lamination packet, whereindespite the unavoidable effects of settling of the bar insulation aswell as of the slot washers and shims, a defined radial bracing andcorrespondingly a tangential bracing as well can be brought to bear.

This object is attained in accordance with a method for assembly anddismantling of a system as defined above, inside the stator boring bymeans of the following steps.

a) the winding bars of one slot segment bar group, which are put intoplace together with wedge strips and optionally pressure pieces andslot-side wave spring strips, into the bar receiving slot between twosuccessive slot teeth, are radially and tangentially pre-stressed bymeans of curved shell plate pieces extending at least from one toothhead to the next and distributed over the axial winding bar length, andare shaped as well as made to pre-settle by means of this prestressingas well as under the influence of temperature; that

b) in the described manner, the slot segment bar groups and theassociated curved shell plate pieces are assembled over the entireinside circumference of the stator lamination packet to makecircumferential units that axially succeed one another with respectivespacing interstices between them, and the associated slot segment bargroups are made to be shaped and pre-settled; and that

c) the individual circumferential units of the shell plates aresuccessively dismantled, beginning at an axially outer end of the statorlamination packet inside circumference and proceeding inward or to theother, outer end and are replaced by the support rings; and that

for dismantling of the support rings and/or individual ones, or all ofthe slot segment bar groups, the support rings are successively replacedin reverse order with curved shell plate pieces, and for dismantling ofindividual slot segment bar groups, the axial set of the particularshell plate are pieces that are located in the circumferential vicinityof the slot segment bar groups to be removed is dismantled.

The advantages attainable with the invention are above all that thesupport rings can engage the inside circumference of the winding bars orslot segment bar groups over a large surface area and with uniformtransmission of force as well as the generation of high radial clampingforces, so that in combination with the tangential bracing, highsecurity against loosening of the winding bars is assured both in poweroperation and in the shortcircuit situation. The support rings are easyto dismantle and reassemble, adjust, test and post-tension.

In conjunction with the drawing, showing a plurality of exemplaryembodiments of the invention, these embodiments will now be described infurther detail.

The drawing, for the most part in simplified, schematic form, shows thefollowing:

FIG. 1 is an axial-normal fragmentary section extending over somewhatmore than one-fourth of the circumference, which shows a first exemplaryembodiment of a fixing system having a support ring and a turnbuckleserving to enlarge its circumference;

FIG. 2 is an axial fragmentary section taken along the line II--II ofFIG. 1;

FIG. 3 is an axial normal fragmentary section of a shell-plate systemfor pre-assembly of the air-gap winding;

FIG. 4 shows the detail IV of FIG. 3 on a larger scale;

FIG. 5 shows the subject of FIG. 3 with a support ring of reduceddiameter, introduced into the stator bore and intended to replace theshell plates;

FIG. 6 shows a support ring which has more than one dividing seam, thatis, one seam for assembly of the turnbuckle and a further seam as adividing seam, the location of the air-gap winding being indicated inthis drawing figure merely by a ring-shaped zone;

FIG. 7 is a radial plan view on the inside circumference of a hydraulicor pneumatic clamping device for the defined prestressing of theparticular support ring, so that the associated turnbuckle cancorrespondingly easily be post-tensioned;

FIG. 8 is a fragmentary section taken along the line VIII-- VIII of FIG.7;

FIG. 9 shows a support ring having flanks opposing one another in themanner of arrowheads, and counterpart flanks, correspondingly embodiedlike the tails of arrows, of the associated turnbuckle, in which theclamping screw is oriented radially;

FIG. 10 shows a further exemplary embodiment of the turnbuckle, in whichthe flanks of the support ring and the counterpart flanks of theturnbuckle are embodied as in the example of FIG. 9, but in which theclamping screw is oriented tangentially and with its two thread endsengages a counterclockwise or clockwise thread of the two turnbucklehalves, respectively;

FIG. 11 is an axial view of a slot and tooth system having winding barsin place in it and a pre-stressed support ring contacting it, shown indetail and with a further embodiment of a turnbuckle;

FIG. 12 is the view XII of FIG. 11 on the inserted turnbuckle, in whichthe axially adjacent two support rings in the associated turnbuckles canbe seen in detail;

FIG. 13 is a fragmentary axial section of a system for fixation of thefinal support ring, as viewed in the axial direction;

FIG. 14 is a fragmentary section taken along the line XIV--XIV of Fig.XIII;

FIG. 15 is a slot and tooth system corresponding to FIG. 11, but inwhich a radial clamping screw, which serves to generate a tangentialinitial tension, is anchored in an axial anchor bolt of the slot tooth;

FIG. 16 is the radial fragmentary view XVI of FIG. 15 showing thepressure piece of rectangular outline;

FIG. 17 shows the detail XVII of FIG. 1, that is, a further embodimentof the wedge bracing for the support rings for generating radialclamping forces, and a wedge bracing independent thereof on both sidesof the slot teeth for generating a tangential initial tension for thewinding; and

FIG. 18 is a variant of the spring-elastic tangential bracing of detailXVIII of FIG. 1, having a slot-side wave spring between two windingwedges.

In FIGS. 1 and 2, a stator lamination packet, identified as an entity asSB, of a dynamo-electric machine, in particular a turbo-generator havingan air-gap winding 3, is shown schematically in a detail showingapproximately one quadrant. The invention relates to the fixing of thisair-gap winding 3 on the inner circumference of the stator laminationpacket SB. The latter, with its inner circumference δ₀, defines thestator bore for the machine rotor R, shown only schematically in itsoutline, rotating in it with the air gap δ₀. The stator laminationpacket SB is composed of a laminated, approximatelycircular-cross-section shielding packet 1 in the so-called yoke region,the individual lamination segments 1.0 of which comprise magneticmaterial, and a slot and tooth system 200 disposed on the insidecircumference of this shielding packet 1 having slot teeth 2 built upfrom nonmagnetic sheet metal, wherein the small plates, of approximatelytrapezoidal outline, of the slot teeth are each rigidly connected, inthe vicinity of the abutment points 2.0, to the respective adjoininglamination segments 1.0 of the shielding packet 1. The connection takesplace in particular in the vicinity of the "seams" or abutment points bymeans of electron beam welding, or laser welding, which is even morefavorable, because this makes it possible to eliminate undesirabledistortion. The seams or abutment points 2.0 in the exemplary embodimentshown are located on circular arcs. However, the invention is notrestricted to this; the decisive factor is that the slot and toothsystem 200, at least in the vicinity of the bore region, comprisesnonmagnetic material, and in particular nonmagnetic steel plates; theabutment points may also have a V- or W-shaped course, by way ofexample. The air gap δ₀ is the magnetic air gap for the field lines. Themechanical air gap δ₁ will be explained later herein.

The schematically indicated winding bars or "bar groups" 3.0 of theair-gap winding 3 are introduced into the circumferential interspaces,serving as axially parallel bar receiving slots sb1, which are eachdefined in the tangential direction by successive slot teeth 2; thesewinding bars 3.0 are fixed in their inserted position by means of aretaining device 400 that can be assembled from the stator bore sb0 andthat rests over a large surface area on the winding bar sides 3.01oriented toward the stator bore and forcing the winding bars or "bargroups" 3.0 against the slot base 1.1. At least in the radially unbracedstate, the winding bars or "bar groups" 3.0 protrude with a radialexcess into the air gap, so that the force lock with the retainingdevice can be established thereby.

As FIG. 1 in combination with FIG. 2 shows, the retaining device,identified as an entity as 400, has a plurality of support rings 4,individually identified as 4a, 4b, 4c, 4d, etc, disposed in successionaxially of the machine. These rings comprise elastically deformableresilient material and are split at at least one point 4.0 on theircircumference (FIG. 1). Because of this dividing seam, it is possible toadjust the support rings by means of diameter enlargement in theirazimuthal initial tension, to generate a radial pre-stressing forceP_(r) engaging the winding bars or "bar groups" 3.0 that is greater thanthe operating force acting in the radial direction. For a winding bar or"bar group" 3.0, the force vectors P_(r) are shown schematically for thesake of illustration. So that this diameter change can be accomplishedeasily and conveniently both during assembly and dismantling as well asduring post-tensioning, inside the stator bore, the support rings 4 areprovided in the vicinity of at least one of their dividing seams 4.0,with a turnbuckle 7. The mechanical air gap δ ₁ is produced between theinside circumference of the support rings 4 and the outsidecircumference of the rotor R.

A first embodiment of this turnbuckle is shown in the detail XVII ofFIG. 17 and includes a turnbuckle wedge 70 and a turnbuckle plate 9connected by clamping screws 8. As this drawing shows, the dividing seamflanks 4.1, 4.2, facing one another at a distance, of the ends of thesupport ring 4 belonging to the turnbuckle 7 extend with a taper fromradially inward to radially outward, so that an approximatelytrapezoidal outline is produced in the axial fragmentary view of FIG.17, and can be brought into engagement with the complementarily shapedcounterpart flanks 7.1 and 7.2 of the tightenable turnbuckle wedge 70 insuch a manner that upon displacement of the wedge 70 in the clampingdirection r1, the pressure per unit of surface area between therespective dividing seam flanks 4.1, 4.2 resting against one another andthe associated counterpart flanks 7.1, 7.2 is increased. Since the wedge70 shown in FIG. 17 extends preferably over the entire axial length b1of the associated support ring 4, a plurality of the clamping screws 8are to be distributed over this length b1, for example three clampingscrews 8 should be distributed uniformly over the length b1. One suchclamping screw 8 (FIG. 17) is supported in a corresponding radiallyoriented bore 7.3 of the wedge 70; this screw is, in particular, asocket-head screw, which as shown is disposed with its head countersunkin the wedge 70. The thread end 8.1 of the clamping screw 8 engages athreaded bore 9.1 of the turnbuckle plate 9, so that when the clampingscrew 8 is tightened, corresponding azimuthal clamping forces, that is,forces oriented in the circumferential direction, are transmitted to thesupport ring 4, widening it and causing the radial clamping forces P_(r)to be transmitted from the support ring to the inside circumference ofthe air-gap winding 3.

The turnbuckle plate 9 is torsionally fixed by means of a separateturnbuckle plate 9.2, which is inserted in a form-locking manner with adovetail profile into the dovetail slot 2.1 of the tooth 2 and with its"vanes" or lateral strip-plate portions 10 forms thread eyes for furtherclamping screws 11. The further

screws 11, with the pressure pieces 11.1 at their ends, engage theradially inner head faces of the wedges 12 used for tangential bracing.A multiplicity of additional clamping screws 11 are distributed over theaxial length of the turnbuckle plate 9 in the threaded bores of thelateral strip plate portions 10, and the turnbuckle plates 9 along withtheir lateral strip-plate portions 10, 9.2 are suitably subdivided intoaxial portions, for example in accordance with the axial extension ofthe support rings 4. If the abutting or associated support ring 4 hasnot yet been installed, then accessibility to the additional clampingscrews 11 is readily possible from the inside circumference of the bore;that is, the stator winding introduced with its winding bars or "bargroups" 3.0 into the bar receiving slots sb1 can be pre-stressed in thetangential direction by means of the tangential clamping wedges 12 andthe associated clamping screws 11. To enable post-tensioning, once theassociated support ring 4 has been installed, the support rings can, asshown in FIG. 2, be provided with suitable bores 13.

From FIG. 1, in addition to the tangential clamping wedges 12, which aredisposed on the side flanks of the slot teeth, still additionalintermediate wedges 14 are also visible. Like the clamping wedges 12,these intermediate wedges 14 are preferably of fiber-reinforced plastic(FvK) of high electrical breakdown resistance. In the middle of the slotand tooth system 200, a system of pressure hoses 15 is shown in FIG. 1,instead of an intermediate wedge 14, in order to indicate that insteadof or in addition to the tangential clamping wedges 12, a pre-stressingof the winding in the tangential direction could also be performed bysuch inflatable pressure hoses 15, which are disposed in the hollowspaces in between two wedge halves 16a , 16b preferably disposedsymmetrically with one another. Such pressure hoses can be subjected toa pressure fluid, the pressure being monitored continuously. However, inthe context of the present invention a spring-elastic tangential bracingachieved by means of slot-side wave springs 50 of FvK (fiber-reinforcedplastic) is preferred; as shown in FIG. 18, these springs 50 should beinserted between the bar groups 300 or bars 3.0 and the wedges 12 or 14(see the variant for system pressure hoses 15, 16a , and two wedgehalves 16b in FIG. 18). Especially with such slot-side wave springs 50,the bracing of the air-gap winding 3 in the tangential direction by theclamping wedges 12 and the clamping screws 11 which form mechanicalwedge bracing means is particularly advantageous, because thencontinuous pressure monitoring, or monitoring for tightness, isunnecessary; a possible post-tensioning in the course of maintenancework is all that is necessary. The slot-side wave springs arepre-stressed in a defined manner; they increase the friction lockingcounteracting pulsation forces in the radial direction.

In FIGS. 1, 2 and 17, reference numeral 5 indicates additional springelements providing the spring-elastic radial bracing, in the presentcase being plastic wave spring strips, while reference numeral 6indicates pressure strips that cover the insides of the bars orientedtoward the wave spring strips 5 and distribute the radial clampingforces P_(r) uniformly to the winding bars or "bar groups". It issuitable to provide further pressure strips 60 on the side of theplastic wave spring strips 5 oriented toward the associated supportspring 4, as indicated in FIG. 17, in order to protect the support ring4 from local overload.

In a highly simplified manner, FIG. 6 shows a second exemplaryembodiment, in which the support ring not only has a partial seam 4.0for assembling the turnbuckle 7, but also a further dividing seam 4.3,and in the vicinity of the other half of the support ring (this half isnot shown) has another dividing seam, so that the support ring 4 comesapart into a total of three curved support ring pieces, which uponassembly can be assembled in a form-locking manner to make a completesupport ring curve. The dividing seam 4.32 represents a preferredembodiment: The two abutting support ring parts engage one another withan arrowhead part 4.31 and an arrow-tail part 4.3. Assembly anddismantling are facilitated by this multi-part arrangement of thesupport ring. The system is otherwise as described in connection withFIGS. 1, 2 and 17.

FIGS. 7 and 8 shows a turnbuckle 7 which is embodied like that of FIGS.1, 2 and 17; for the sake of a simpler drawing, the strip plate portions10, clamping screws 11 and clamping wedges 12 are not shown here. InFIGS. 7 and 8, the intent is simply to explain a hydraulic or pneumaticclamping device SV, which has two solid pressure strips 17 locatedopposite one another and spaced apart from one another by a distance al,which are variable in their mutual spacing by means of two fluidic powerpiston and cylinder systems 18 disposed one at each end of the strips.The cylinder is shown at 18.1 and the power piston at 18.2. Theillustration is merely schematic, omitting the fluid hoses and fluidvalves used for actuation. The pressure strips 17, which are adapted intheir outer contour to the circular inside contour of the associatedsupport ring 4, are rigidly coupled by means of anchoring bolts 19 tothe end regions of the support ring 4 on both sides of its dividing seam4.0. As FIG. 7 shows, three such anchoring bolts 19 are provided perpressure strip 17; the two ends of the support ring 4 to be brought intoengagement thereby correspondingly each have three receiving bores 4.4.Accordingly, by means of the hydraulic or pneumatic clamping device SV,the associated support ring 4 can be spread apart in its azimuthaldirection and then the locking wedge 70 can be adjusted with itsclamping screw 8. After the adjustment of the locking wedge 70 and theunclamping of the system 18, the clamping device SV can then easily bedismantled and put back into position on the next support ring that isto be clamped. FIG. 9 shows the embodiment of a turnbuckle 7 in whichthe dividing seam flanks 4.1, 4.2 facing one another at a distance ofthe ends of the support ring 4 that belong to the turnbuckle extend suchthat they taper from radially inward to radially outward over at leastpart of the length r91, while over an adjoining radial portion r92, inthe form of flanks 4.5, 4.6, they do not taper in wedge-like fashion butinstead widen again in wedge-like fashion, so that the two ends of thesupport ring 4 form arrowhead-like protrusions oriented toward oneanother in azimuthal fashion and facing one another in pairs. Theprotrusions are shown at 40 and 41. Arrowhead-like protrusions on thefacing ends of the support ring 4 have the advantage that the clampingforces of the locking wedge engaging them, the locking wedge in thepresent case comprising two parts 71 and 72, produce inwardly orientedforce components, as a result of which the ends of the support ring 4cannot spread apart or open. The part 72 at the same time performs thefunction of a turnbuckle plate, and because of its rectangular outlinethis second locking wedge 72 is at the same time torsionally fixed onthe facing flanks 4.5, 4.6.

In the example of FIG. 9, the clamping forces oriented in the radialdirection r1 are converted into azimuthal spreading forces indicated bythe arrows az1, az2, which in turn, by contact with the insidecircumference of the air-gap winding 3, lead to the radial bracingforces P_(r) already mentioned. In the example of FIG. 10, thearrowhead-like end contour of the ends of the support ring 4 has beenmaintained, but the turnbuckle 7 here has arrow-tail-like recesses onpressure pieces 73, 74 resting against the support ring ends, and thesepressure pieces, by means of a plurality of forcing screws 20distributed over their axial length, lead to the azimuthal spreadingapart of the support ring 4 in the direction of the arrows az1 and az2.The forcing screw 20 is suitably provided with a counterclockwise threadon one end and a clockwise thread on its other end and is supported incorresponding threaded bores of the pressure pieces 73, 74; referencenumeral 21 indicates a check nut. By engaging the nut 20.1 of theclamping screw 20 with a threaded wrench, a spreading apart can beattained, but in this embodiment, because of the high clamping forces,the hydraulic clamping device of FIGS. 7 and 8 is used forpre-stressing, and in the spread-apart state an adjustment of theclamping nut 20 then takes place.

A fourth exemplary embodiment for a turnbuckle 700 will now be describedin connection with FIGS. 11-14; its clamping direction is not the radialdirection r1, but rather a direction x1 located parallel to the axialdirection of the machine. The locking wedge 70 (see FIG. 12) has anapproximately trapezoidal bottom face, viewed in the radial direction ofits installed state, and has an adjusting screw 701 oriented in itsaxial insertion direction xl and let into the rearward end of thelocking wedge 70; with the shaft end 702 of this screw that protrudesbeyond the contour 22 of the support ring 4, the locking wedge 70 of theturnbuckle 700 of an axially adjacent support ring 4 can be brought intoabutment. It is thus attained that with axially aligned turnbuckles 700of the axially successive assembled support rings 4, the precedinglocking wedge 70 in any aligned pair is fixed in its adjusted positionby means of the locking wedge 70 that follows it. The first and lastsupport ring 4 in the axial set must be axially fixed against the slotand tooth system 200, as will now be described in conjunction with FIGS.11, 13 and 14.

These drawings show the axial channel 23 in the slot teeth. Cylindricalabutment bodies 24 that fit them are introduced into these axialchannels 23, which are of circular cross section; the abutment bodiesare preferably of non-magnetic steel, and their jacket, like theirthreaded bore 24.1, is provided with an insulating plastic layer. Theabutment bodies 24 can also be made entirely of FvK. The threaded bore24.1 of the abutment bodies 24 points precisely in the radial direction,so that radial fixation screws 26, lined with hollow-cylindricalpressure sleeves 27, can be inserted through corresponding radial bores25 and with their ends screwed into the abutment bodies 24. The pressuresleeves 27 fit precisely into the bores 25, so that the associatedsupport ring 4 is thereby blocked against axial movement. This axialblocking according to FIGS. 13, 14, as mentioned, is provided on bothaxial ends of the stator lamination packet SB.

To return to the turnbuckle 700 of FIGS. 11 and 12: It can be seen thatthe adjusting screw 701 is embodied as a stud bolt, and is supportedwith its threaded shaft in a corresponding threaded blind bore 703 ofthe rearward end of the associated blocking wedge 70 and on a free endadjacent to the threaded shaft has a threaded polygon 704 for access bymonkey wrenches or the like. The threaded polygon 704 is then followedby an end 702 of the adjusting screw 701. In the vicinity of the freeadjusting screw end 702, the rearward end of the associated blockingwedge 70 is recessed somewhat, as shown, and the contacting end face ofthe adjacent support ring 4 is recessed in the form of the recess 28,for the sake of accessibility to the threaded polygon 704. Since theaxial length of the associated support ring 4 is greater by a multiplethan its radial thickness, the respective locking wedge can be providedwith a small wedge angle of 10° (angle at the tip of the wedge). Thiskind of small wedge angle produces self locking, when FvK(fiber-reinforced plastic) is the material used. This considerablyfacilitates assembly and dismantling of the support rings, because theassembled and already wedged-together support ring needs no furtherlocking during the assembly process. The additional mutual locking ofthe locking wedges 70 with one another, with the and of the adjustingscrews 701, is accomplished, with a view to the forces of impact andvibration, during the operation of the electrical machine.

The wedge flanks at the ends of the support ring in the vicinity of thedividing seam 4.0 are once again embodied in the manner of arrow heads,but the dividing seam flanks 4.1', 4.5' and 4.2', 4.6' taper in thedirection xl in accordance with the indicated wedge angle and as can beseen in dashed lines in FIG. 11. With this system as well, it issuitable to use an additional hydraulic clamping tool as indicated inFIG. 7 and FIG. 8.

FIG. 11 shows still another detail: Between the wave springs 5 and thesupport rings 4, flat spring guide beds 29 of U-shaped cross section areintroduced, the wave springs 5 being received by the U-shaped channel ofthe spring guide beds. The legs of the U comprising the spring guidebeds 29 protrude radially into the free interstices that remain as, aresult of the rounding off of the edges of the winding bars or "bargroups" 3.0. The spring guide beds always assure an unequivocallydefined position of the wave springs 5.

FIGS. 15 and 16 show a system for tangential bracing of the air-gapwinding 3 that is modified by comparison with the embodiment of FIGS. 1,2 and 17, and in this embodiment the winding bars 3.0, or the slotsegment bar groups made up of a plurality of bars, are supported withinitial tension by means of pressure pieces 30 disposed at the top ofthe slot teeth 2, and these pressure pieces 30 are retained by means ofclamping screws 110 disposed in the vicinity of the slot teeth andanchored in abutments 24 of the stator lamination packet SB. As can beseen from FIG. 15, the pressure pieces 30 and the clamping screws 110are recessed radially outward with their heads 110.1 with respect to theoutside circumference of the support rings 4. For the sake of thetangential pre-stressing of the winding bars or "bar groups" 3.0, thepressure pieces 30 engage the heads of wedges 12, which--as in the firstembodiment of FIGS. 1, 2 and 17--are inserted into wedge intersticesbetween the slot teeth 2 and the respective side of the winding bar incontact with them. The disposition of the axial channels 23 and of thecylindrical abutment bodies 24 inserted into them, with their threadedbores 24.1, is as has already been explained in connection with FIGS. 13and 14. In FIG. 11, the elements for tangential bracing have not beenshown, for the sake of simplicity. Similarly to the illustration of FIG.14, in the tangential bracing means of FIGS. 15 and 16, one opening 31is provided in each support ring 4, in radial alignment with the headsof the clamping screws 110, so that a clamping tool can engage the heads110.1 of the clamping screws 110 through these openings 31 from theinside circumference of the stator bore. In this manner, the adjustmentof the tangential bracing by means of the clamping screws 110 can beaccomplished independently of the radial bracing by means of the supportrings 4 and their turnbuckles 7 or 700, which is of particularimportance because of the considerable pulsating radial and tangentialforces that arise during operation. The pressure piece 30, which may beof steel or fiber-reinforced plastic, is embodied as a plate spring,which is pre-curved and flattens somewhat when the clamping screw 110 istightened, resting with its flat long edges on the heads of the wedges12 and pressing them farther into their wedge slots, so that as a resultcorresponding tangential bracing forces are exerted upon the air-gapwinding or upon its individual winding or "bar groups" 3.0.

FIGS. 3-5 further illustrate the preferred method for assembly anddismantling of a system in accordance with the above-described FIGS. 1,2, 17 as well as 6-16. FIG. 3 shows curved shell plates 32, which havethe axial width of the support rings 4 to be introduced later, as wellas approximately their radial thickness. In the circumferentialdirection, they extend from one tooth 2 to the next tooth with a certainexcess length, so that in this region they can be fixed by means of theradial clamping screws 8 to the turnbuckle plates 9. Preferably, shellplates 32 adjacent one another mesh with one another with teeth in thistooth region, so that one or the other shell plate 32 can be fixed inalternation by means of the clamping screws 8. The above-mentionedsandwich system comprising pressure strips 6, wave springs 5 andadditional pressure strips 60 can be associated with the slot segmentbar groups or bars 3.0 of the air-gap winding 3, which are introducedinto the bar receiving slots sb1, and with the shell plates 32, which issummarily suggested in the drawing by means of a shaded strip. Duringthis pre-assembly of the air-gap winding 3, however, an intermediatelayer 33 comprising pneumatic cushions can also be disposed between theshell plates 32 and the air-gap winding 3. In other words, once thecorresponding slot segment bar group 300 has been put into plate in itsslot sb1, the curved shell plate pieces 32 are assembled, and as aresult the bar group 300 is pre-stressed both tangentially and radially.The means for tangential pre-stressing have not been shown in FIGS. 3and 4; they may be embodied in the manner described in conjunction withFIG. 17 or FIG. 15. With this pre-stressing taking place and under theinfluence of temperature, the associated bar group 300 is then formed,and also, along with its winding insulation, made to pre-settle; thatis, a change in shape of the bar groups 300 or individual bars 3.0 thatlater arises during operation in response to electrical, mechanical andtemperature stress, is made to happen beforehand. In the mannerdescribed, all the slot segment bar groups 300 with the associatedcurved shell plate pieces 32 are assembled over the entire insidecircumference of the stator lamination packet SB to form circumferentialunits that succeed one another, each spaced apart from another withinterstices between, and the associated slot segment bar groups 300 arecaused to be shaped and pre-settled under the influence of temperature.

The individual circumferential units of the shell plates or shell platepieces 32 can now be progressively dismantled in succession, beginningat an axially outer end of the stator lamination packet insidecircumference, and proceeding inward or toward the other, outer andreplaced with the support rings 4. The dismantling of the shell platesand their successive replacement can also be begun in the middle of thestator lamination packet, then proceeding toward both axial ends. FIG. 5shows that a support ring 4 the diameter of which is reduced by means ofpushing its ends over one another can easily be inserted into theinterior of the stator lamination packet SB defined by the insidecircumference of the shell plate curve. After the removal of the shellplate curve, which is to be replaced by the support ring 4, the supportring can then be assembled.

If it is desired to dismantle individual support rings or all of thesupport rings, then the procedure can be performed in reverse, and onesupport ring after another can be replaced by corresponding shell platecurve segment assemblies. Once this has been done, then for removal of aparticular slot segment bar group, the particular shell plate piecesthat are located in an axial set and in the circumferential vicinity ofthis bar group to be removed can be dismantled. After re-assembly of theparticular bar group, or assembly of a new bar group, the curved shellplate pieces of this axial set can be re-assembled once again. Then thesuccessive replacement of a curved shell plate piece system can takeplace over its entire circumference by means of a support ring, in axialsteps, until the entire inside circumference of the machine is againsupported by the support rings.

We claim:
 1. In a high-power dynamo-electric machine including:A) astator lamination packet with an inner periphery defining a stator borefor a machine rotor revolving with an air gap at a given operatingforce, said stator lamination packet having:A1) a laminated screeningpacket with an inner periphery, a yoke region having an approximatelycircular-annular cross section, and lamination segments formed ofmagnetic material, and A2) a slot and tooth system disposed on the innerperiphery of the screening packet, the slot and tooth system beingformed of nonmagnetic material at least in the vicinity of the statorbore and having abutment points being distributed over the innerperiphery of the screening packet and slot teeth, successive slot teethtangentially defining circumferential interstices serving as axiallyparallel bar receiving slots with a slot bottom, the slot and toothsystem being rigidly connected to the screening packet at the abutmentpoints, and B) an air-gap winding on the inner periphery of the statorlamination packet having winding bars with winding bar sides orientedtoward the stator bore, the winding bars being inserted in thecircumferential interstices with a radial protrusion beyond the slotteeth into the air gap, a system for fixing the air-gap winding on theinner periphery of the stator lamination packet, the systemcomprising:a) a retaining device mounted from the stator bore, restingagainst the winding bar sides, pressing the winding bars against theslot bottom, and fixing the winding bars in position, said retainingdevice having a multiplicity of support rings being mutually aligned inaxial direction of the dynamo-electric machine and having circumferencesand outer peripheries, said support rings being formed of elasticallydeformable resilient material, being divided by dividing seams at leastat one point along the circumferences thereof, b) a turnbuckle insidethe stator bore in the vicinity of at least one of said dividing seamsvarying the diameter and adjusting azimuthal prestressing of saidsupport rings for diameter enlargement in order to generate a radialprestressing force engaging the winding bars being greater than thegiven operating force, for diameter variations upon assembly anddismantling and for post-tensioning of said support rings, c) saidturnbuckle comprising a turnbuckle plate disposed at said outerperipheries of said support rings, a tensionable locking wedge in saiddividing seams having a rearward end portion, and an adjusting screwsoriented in an axial insertion direction and disposed in said rearwardend portion, as viewed in radial direction when installed, saidadjusting screw having a shaft end protruding beyond said support ringand threadedly receiving in a threaded bore formed in said turnbuckleplate, said locking wedges of said turnbuckles of axially adjacentsupport rings being in mutual contact with axially aligned turnbucklesof axially aligned and assembled support rings disposed in mutual axialalignment.
 2. System according to claim 1, wherein said dividing seamsdefine lateral surface of said support rings facing one another at adistance, said lateral surfaces being at least partially tapered fromradially inward to radially outward, and said tensionable locking wedgehas counterpart lateral surfaces corresponding in shape to and being inengagement with said lateral surfaces of said support rings, wherebypressure exerted per unit of surface area between said lateral surfacesof said support rings and said counterpart lateral surfaces beingincreased upon displacement of said locking wedge in a given clampingdirection.
 3. System according to claim 2, wherein said lateral surfacesof said support rings have adjoining partial lengths, one of saidpartial lengths being tapered from radially inward to radially outwardand the other of said partial lengths being widened from radially inwardto radially outward forming arrowhead-like protrusions andarrow-tail-like recesses on two of said support rings being azimuthallyaligned and facing one another in pairs.
 4. System according to claim 2,wherein said turnbuckle is clamped by relative displacement of saidcounterpart lateral surfaces of said locking wedge with respect to saidlateral surfaces of said support rings in radial direction.
 5. Systemaccording to claim 3, wherein said lateral surfaces of said supportrings and said counterpart lateral surfaces of said locking wedge aretapered in wedge-like fashion in an axial insertion and clampingdirection of said locking wedge having a wedge angle producingself-locking.
 6. System according to claim 1, wherein said adjustingscrew is a stud bold having a threaded shaft supported in a threadedblind bore formed in said rearward end portion of said locking wedge,and said stud bolt has a free end adjoining said threaded shaft having athreaded polygon and having said protruding shaft end adjacent thereto,and said rearward end portion of an associated locking wedge having arecess formed therein in the vicinity of said free end of said adjustingscrew providing accessibility to said threaded polygon.
 7. Systemaccording to claim 1, wherein said adjusting screw is a stud bolt havinga threaded shaft supported in a threaded blind bore formed in saidrearward end portion of said locking wedge, and said stud bolt has afree end adjoining said threaded shaft having a threaded polygon andhaving said protruding shaft end adjacent thereto.
 8. System accordingto claim 1, wherein said support rings are formed of fiber-reinforcedsynthetic resin.
 9. System according to claim 1, wherein said slot teethhave tops, the stator lamination packet has abutments, and includingpressure pieces being disposed on the top of the slot teeth andsupporting the winding bars with prestressing, clamping screws disposedradially in the vicinity of the slot teeth and anchored in the abutmentsof the stator lamination packet for retaining said pressure pieces, saidpressure pieces and said clamping screws having heads being radiallyoutwardly recessed with respect to the outer peripheries of said supportrings, and wedge strips having heads engaged by said pressure pieces fortangential prestressing of the winding bars, said wedge strips beinginserted into the interstices between the slot teeth and a respectivewinding bar side.
 10. System according to claim 9, wherein the statorbore has an inner periphery, and said support rings having openingsformed therein in radial alignment with said heads of said clampingscrews through which a clamping tool can engage said heads of saidclamping screws from the inner periphery of the stator bore.
 11. Systemaccording to claim 1, including spring elements inserted between theouter peripheries of said support rings and said winding bar sides. 12.System according to claim 11, wherein said spring elements arestrip-like wave springs.
 13. System according to claim 23, includingpressure strips disposed under said wave springs toward said winding barsides.
 14. System according to claim 12, including spring guide bedswith flat U-shaped cross sections disposed between said wave springs andsaid support rings, said U-shaped cross sections having U-shapedchannels receiving said wave springs.
 15. In an electric machineincluding:A) a stator lamination packet having:A1) an inner peripherydefining a stator bore, A2) a laminated screening packet with an innerperiphery and lamination segments formed of magnetic material, and A3) aslot and tooth system disposed on and connected to the inner peripheryof the screening packet, the slot and tooth system being at least partlyformed of nonmagnetic material and having successive slot teeth definingbar receiving slots with a slot bottom, and B) an air-gap winding on theinner periphery of the stator lamination packet having winding bars withwinding bar sides oriented toward the stator bore, the winding barsbeing inserted in the bar receiving slots with a radial protrusionbeyond the slot teeth, a system for fixing the air-gap winding on theinner periphery of the stator lamination packet, the systemcomprising:a) a retaining device pressing the winding bar sides againstthe slot bottom, said retaining device having an multiplicity of elasticsupport rings being mutually aligned in axial direction of the electricmachine and having outer peripheries, said support rings having at leastone dividing seam formed therein, b) a turnbuckle inside the stator borein the vicinity of said at least one dividing seam for varying thediameter and adjusting azimuthal prestressing of said support rings, c)said turnbuckle comprising a turnbuckle plate disposed at said outerperipheries of said support rings, a tensionable locking wedge in saiddividing seam having a rearward end portion, and an adjusting screworiented in an axial insertion direction and disposed in said rearwardend portion, as viewed in radial direction when installed, saidadjusting screw having a shaft end protruding beyond said support ringand threadedly received in a threaded bore formed in said turnbuckleplate, said locking wedges of said turnbuckles of axially adjacentsupport rings being in mutual contact with axially aligned turnbucklesof axially aligned and assembled support rings disposed in mutual axialalignment.